Granular flow, such as hopper discharge and debris flows, involves complex multi-scale, multi-phase, and multi-physics coupling, posing significant challenges for numerical simulation. Over the past two decades, methods like the Discrete Element Method (DEM), Smoothed Particle Hydrodynamics (SPH), and Depth-Averaging Method (DAM), have been developed to address these problems. However, their applicability across different scales remains unclear due to differences in physical assumptions and numerical algorithms. Therefore, a comprehensive evaluation is critically needed. This study selects three typical methods (DEM, SPH, and DAM) to examine their convergence behavior, boundary condition implementation, and limitations in physical and numerical modeling. We numerically studied three extreme deformation flow cases with the three chosen methods. These cases include granular column collapse at the particle scale, flow-structure interaction at the laboratory scale, and reconstruction of the 2015 Shenzhen Guangming landslide at the field scale. By comparing the granular flow dynamics, deposition morphology, and structure interactions, and also the simulation accuracy and computational efficiency, we show the applicability of the three models across different scales. Further, we provide practical guidance for model selection in large-deformation flow problems in a granular system of different scales.
Tian et al. (2026) studied this question.